Patients for whom normal ingestion of food becomes difficult or impossible may require placement of a feeding tube to assist in providing their nutritional needs. For some individuals, such as comatose patients, stroke victims, or those with a compromised gastrointestinal tract, this may require introduction of a feeding tube for delivery of nutritional products directly into the stomach or the jejunum. Tubes for delivery of nutritional products into the stomach are generally referred to as gastrostomy tubes, or “G”-tubes. Tubes for delivery of nutritional products into the jejunum are generally referred to as jejunostomy tubes, or “J”-tubes. In many cases in which a J-tube is utilized, the J-tube is inserted through the interior of a previously positioned G-tube.
There are two general methods for percutaneously positioning a gastrostomy tube in a patient, a procedure generally known as a Percutaneous Endoscopic Gastrostomy (PEG). One such method, referred to as the Ponsky (“pull”) method involves introduction of an endoscope through the patient's mouth and esophagus and into the stomach. The endoscope contains a light source having sufficient power such that the position of the endoscope can be visualized on the outside of the patient's abdomen. An incision is made through the abdominal wall, then a trocar needle is passed therethrough into the stomach and is visualized by the endoscope. The needle is removed, leaving the trocar. A looped wire is passed through the trocar and is grasped/captured by a snare/forceps (usually disposed through a working channel of the endoscope). The endoscope, snare/forceps, and wire are pulled up through the esophagus and out through the mouth. The wire is then fastened with a knot or other means to the end of the gastrostomy tube, which often includes a dilator portion having a leading lower-diameter portion that expands to the full gastrostomy tube diameter along its length. This assembly is then pulled back down through the esophagus and stomach. The leading end of the wire and the external portion of the gastrostomy tube are pulled out through the aperture in the abdominal wall initially formed by the trocar needle. Typically, an internal bolster, such as a balloon, is provided internal of the stomach to hold the stomach against the abdominal wall, and an external bolster is provided external of the abdomen for anchoring the device exterior of the patient's skin.
The other method is commonly referred to as the “push” method. In this method, the endoscope is used to provide the physician with visualization of the stomach. An incision is made through the abdominal wall, then a trocar needle is passed therethrough into the stomach and is visualized by the endoscope. The needle is removed, leaving the trocar. A wire guide is passed through the trocar and is grasped/captured by a snare/forceps (usually disposed through a working channel of the endoscope). The endoscope, snare/forceps, and wire are pulled up through the esophagus and out through the mouth. the gastronomy tube (commonly with a leading dilator) is threaded over the wire guide. Then, the gastronomy tube assembly is advanced (“pushed”) over the wire through the mouth, esophagus, and stomach to the incision. When it is visible through the incision, the assembly is pulled until its internal bolster contacts the interior wall of the stomach. Following placement via either of these two methods, proper positioning of the internal bolster against the stomach wall may be confirmed with the endoscope. Further background on relevant techniques may be understood with reference to PCT Pat. Publ. No. WO2010/075032 to Farrell et al., which is incorporated herein by reference.
In both procedures, the process of directing the dilator and/or gastrostomy tube through the abdominal wall can cause “tenting.” “Tenting” is the distortion of body wall tissue being pushed/pulled away from the patient's body core as it frictionally contacts the outer circumference of the dilator and/or gastrostomy tube being directed therethrough. Many physicians would prefer to avoid this tissue distortion.
It may be desirable to provide to provide a dilator and/or gastrostomy tube that minimizes tissue displacement during introduction of the gastrostomy tube and that—by minimizing or preventing tenting—will improve physician's perception and performance of the procedure.